The objective of this project is to characterize glycerol permease and glycerol kinase in a line of human tumor cells and to determine which of these two proteins limits the rate of utilization of exogenous glycerol. Effects of thyroid and adrenal cortical hormones on the levels of these two proteins and those of the cytoplasmic NAD-dependent glycerol 3-phosphate dehydrogenase and the mitochondrial FAD-dependent glycerol 3-phosphate dehydrogenase will be investigated. Mutants lacking specific proteins of the glycerol system will be sought and characterized with the aim of eventual identification of all the structural genes of this system and the genetic elements which control their expression.